U.S. Pat. No. 4,608,418 to Czerwinski et al. teaches hot melt urethane compositions formed from a mixture of a long chain polyol, a chain extender, an isocyanate or isocyanate prepolymer, and a plasticizer. Optionally, various resins including epoxy resins also may be dissolved in the plasticizer and incorporated into the composition. A hot melt composition generally is one applied in the molten state, at temperatures of about 250.degree. F. (121.1.degree. C.) to 450.degree. F. (232.2.degree. C.), and having a viscosity in that condition (Brookfield viscometer) of less than about 50,000 cps, preferably less than about 25,000 cps. When cooled to room temperature, such compositions are solids that are elastomeric in nature. These compositions are formed by heating the reactants at temperatures of at least about 330.degree. F. (165.6.degree. C.), preferably at about 350.degree. F. (176.7.degree. C.) to about 450.degree. F. (232.2.degree. C.) for 2 or 3 hours.
U.S. Pat. No. 4,870,142 to Czerwinski et al. teaches thermoplastic hot melt compositions formed from a mixture of one or more polyisocyanates, one or more hydroxyl terminated polyols and/or one or more chain extenders, and one or more epoxy resins.